An uninterruptible power supply (UPS), also known as a continuous power supply (CPS) or battery backup, is a device that maintains a continuous supply of electric power to connected equipment, such as, for example, computers or telecommunications equipment, by supplying power from a separate source when a normal power source is not available. A UPS differs from an auxiliary power supply or standby generator, which does not provide instant protection from a momentary power interruption. A UPS can be used to provide uninterrupted power to equipment for a certain duration, for example, thirty minutes, until a generator can be turned on or until the normal power source is restored. Integrated systems that have UPS and standby generator components are often referred to as emergency power systems. There are different types of UPS systems. A UPS system may remain idle until a power failure occurs and then quickly switches from utility power to its own power source, or may continuously power the protected equipment from its energy reserves stored in a battery or flywheel while simultaneously replenishing its reserves from another power source. Most types of UPS systems use timers to regulate certain functionality. Such timers use system resources, and a large number of timers can greatly increase the overall cost of a system. This is also true for most embedded systems.